INSECTS. 133 
Note.—In France and Italy four days are required to form the 
cocoon, while in England and certain parts of India forty-six days are 
necessary for its completion ; 360 of these cocoons weigh 14 pound. 
In the United States the Zelia polyphemus is valued for its silk. Little 
windows have been cut in their cocoons and mica inserted, so that the 
growth of the chrysalis might be observed. 
Vatue.—The silk goods produced yearly in the United States alone 
are valued at $27,000,000. 
Fic. 168.—Death's-head moth. 
Hawk-Moths (SpAingide).—The hawk-moths are 
large, swift-flying insects, with stout, spindle-shaped bodies, 
the tongue remarkable for its length. The curious death’s- 
head moth (Fig. 168) belongs to this family. 
VaLuE.—The moths fertilize flowers, carrying pollen from yne to 
another, often attached to their eyes (Fig. 164). 
